Egyptian protesters chant slogans against President Mohamed Morsi in Tahrir Square in Cairo, Tuesday, Nov. 27. Egyptians flocked to Cairo's central Tahrir square on Tuesday for a protest against Egypt's president in a significant test of whether the opposition can rally the street behind it in a confrontation aimed at forcing the Islamist leader to rescind decrees that granted him near absolute powers.

But whether they can organize themselves enough to make him back down is unclear.

Egypt's secular and liberal opposition has been wracked by divisions since the uprising that toppled former President Hosni Mubarak 22 months ago, allowing Islamist parties to dominate the country's democratic transition. But last week's decision by President Morsi, an Islamist, to eliminate most of the checks on his power and protect a controversial constitutional committee from dissolution may have finally given the various opposition groups what they need most: a cause they can all rally around.

Unable to put aside personal politics and infighting and build sufficient grassroots networks to challenge the already-established Islamist groups, secular parties captured less than a quarter of the seats in the first elected parliament after the uprising. The opposition's current disarray means it is unlikely to successfully press Morsi to reverse his decision on its own, say analysts.

Now, many are waiting to see whether Egypt's opposition can work together long enough to mount a sustained challenge to Morsi and his backers, or if they will repeat the mistakes of the last year and a half.

For the moment, Morsi's decree has united most of the non-Islamist, and even some moderate Islamist, groups in Egypt and brought tens of thousands of people to Tahrir Square.

"This is a very big test for the opposition because they have a cause that they can defend. And it's a very strong cause and a big cause and a public cause, and I think it's a very good chance for the opposition to build its base and rally the streets and rally people," says Bassem Sabry, a blogger and writer. "But the test is not 'can the opposition band together in three days?' The question is how they can band together for three months, and another three months after that."

'Uncharted territory'

Last week Morsi issued a constitutional decree declaring his decisions immune from judicial review until a new constitution is written. He also declared that the committee writing Egypt's new constitution, and the upper house of parliament, are protected from being disbanded by a court decision. A court dissolved the first constituent assembly earlier this year, and a second case due to be decided soon could lead to the same outcome for the second body.

Parliamentary elections, to replace the body dissolved by the courts, are scheduled to take place only after a new constitution is adopted in a national referendum. In the absence of an elected parliament, Morsi holds legislative power as well as executive. By sidelining the judiciary, he removed nearly all checks on his power.

Morsi says the move was not an attempt to grasp unlimited power, but was necessary to keep the judiciary, which includes Mubarak appointees many consider corrupt, from putting up endless roadblocks on Egypt's transition to stability. His critics say it places near dictatorial power in his hands.

The president met yesterday with the country's highest judiciary body to try to keep judges from mounting a rebellion against his edict, but the resulting statement – that only Morsi's decisions on vaguely defined "sovereign matters" were immune from judicial review – did not satisfy opposition leaders, parties, and unaffiliated Egyptians, who gathered by the thousands in Tahrir Square today.

The Muslim Brotherhood cancelled a large protest it had called in Cairo in support of Morsi, for fear the two groups would clash. Brotherhood demonstrations were reportedly planned for other cities, however.

On Nov. 24, dozens of political parties, opposition groups, and former presidential candidates announced that they would work together against the president's decree, and called for today's protest. Their ranks included popular figures such as Hamdeen Sabbahi, who garnered about 20 percent of the votes in the first round of presidential elections this year.

"It's kind of a new degree of coordination and new degree of unity that hasn't been done before. So it's kind of new uncharted territory," says Mr. Sabry, who adds that the opposition is focused on the president's decree, and not the president himself. "The question is how to keep the momentum rising, while avoiding any form of violence or unintended consequences."

Since the uprising, secular groups have exhibited not just divisions, but what critics call undemocratic tendencies. When Islamist parties won the majority of the seats, some secularists hoped for military intervention in the political process to weaken Islamists. Some also cheered when a court, backed by the military, disbanded the elected parliament. Secular parties sometimes appear more concerned with defeating Islamists than with plans for Egypt's future, say critics.

Playing the long game

It's unclear whether Morsi's decree can mobilize the sheer numbers that would be needed to force him to back down, says H.A. Hellyer, a Cairo-based fellow at the Brookings Institution. The opposition likely lacks both the popular support or institutional backing needed to force Morsi to reverse his decision.

Instead they may have to focus on long-term plans, such as mobilizing a "no" vote in the referendum on the new constitution if they don't support the document put forward and building a network of support for the next parliamentary elections, he says.

Most liberal, secular, and Christian members of the constituent assembly, about 25 percent of the committee, have resigned, saying that the assembly was dominated by Islamists who were determined to put their stamp on the constitution, and ignored suggestions by secular members. They say the assembly, which was elected by the now-disbanded parliament, is writing a constitution that will allow Islamists to impose their views on the population, and does not sufficiently protect rights of minorities and women.

If opposition parties are unhappy with the constitution, they could start now to mobilize a vote against it, and also begin building the grassroots support necessary to increase their representation in the next parliament, says Hellyer. Parliamentary elections are scheduled to take place after the constitutional referendum, likely in mid-2013.

"They've got a good nine to 12 months before parliamentary elections. The question is, are they going to take advantage of that?" says Hellyer. "If they really want to do this, they have to swallow their pride, accept this is a transitional phase of the revolution, which means you don't get to mark out your turf –you have to choose a strategic objective and focus on that. And once this is done you can go back to your little squabbles and ideological differences."

Unity already fragmenting

Mohamed Aboulghar, head of the secularist Egyptian Social Democratic Party (ESDP), says non-Islamist parties in Egypt are mobilizing their supporters today, bringing in busloads of party members from outside Cairo and calling all party supporters in the capital to come to Tahrir Square.

Opposition figures who attended a Saturday meeting agreed not to negotiate with the president or his administration unless he announces he is willing to cancel or significantly alter the constitutional declaration. They have turned down many attempts at dialogue, he says.

Less than a week after Morsi's decree, some cracks are already appearing among the secular crowd. Some groups are angry that figures who were connected to Mubarak's regime are included in the coalition against Morsi's constitutional declaration. One such figure is Amr Moussa, a longtime foreign minister for Mubarak who left his administration a decade before the uprising.

Secular parties appear to be still in the discussion phase on long-term plans regarding the constitutional referendum and parliamentary elections, tasking a group to study whether the parties should oppose the new constitution in the referendum, or promote a boycott, Dr. Aboulghar says.

Aboulghar says the constitutional declaration took him by surprise because two weeks ago the president invited the leaders of all political parties that were elected to the last parliament to a meeting, and asked their opinions on how to solve the deadlock over the constitution.

"So he was very eager to find a solution, and he didn't open his mouth. He didn't have any comments, he just welcomed us and said 'I want to hear from you. What is your position on how can we sort out the problem?'"

The president's sudden decision to protect the constituent assembly from dissolution after he indicated a desire to seek consensus in the meeting is a sign that the Muslim Brotherhood, in which Morsi was a longtime leader, is dictating his decisions, says Aboulghar. Or perhaps he did not like the Aboulghar's suggestion – dissolving the assembly and starting over, a delay Morsi has indicated he thinks Egypt can't afford.